1. Technical Field
This application relates to the field of data communication, and more particularly to the field of digital data communications using networks.
2. Description of Related Art
A Virtual LAN (VLAN) is created on Layer 2 switches to control broadcasts and enforce the use of a Layer 3 device for communications. A VLAN may be maintained in a database of a local switch. If a VLAN is not known to a switch, the switch cannot transfer traffic across any of its ports for that VLAN. By using VLANs, the same user can be spread out over various geographical locations and still remain in a particular IP subnet.
A VLAN ID is an identification of the VLAN, which is used in connection with the 802.1Q standard that governs deployment of VLANs. The VLAN ID, which is used to identify which frame belongs to which VLAN, has twelve bits and thus allows the identification of 4096 (212) VLANs. Of the 4096 possible VLAN IDs, a VLAN ID of zero is used to identify priority frames and a VLAN ID of 4095 (0xFFF) is reserved. Accordingly, a maximum number of possible unique VLAN IDs is 4,094.
A network management system may be used to discover components for multiple networks, each of which may have its own set of VLAN IDs used within the network. However, given the limited number of unique VLAN IDs, multiple networks may use the same VLAN IDs or VLAN numbers. When the network management system tries to discover VLANs in multiple networks having the same VLAN IDs, the system may not be able to uniquely discover VLANs having the same ID and thus may not be able to manage the VLAN IDs across all of the different networks being managed. One way to address this is to have a user provide unique identifiers for each network, but this may not be practical and probably will not result in consistent naming conventions.
Accordingly, it is desirable to provide a mechanism that automatically and consistently discovers VLAN IDs for VLANs in multiple networks in a way that avoids overlap of VLAN IDs.